Patch "ftrace: Add more checks for FTRACE_FL_DISABLED in processing ip records" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

ftrace: Add more checks for FTRACE_FL_DISABLED in processing ip records

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ftrace-add-more-checks-for-ftrace_fl_disabled-in-processing-ip-records.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Steven Rostedt (Red Hat)" <[email protected]>
Date: Mon, 14 Nov 2016 16:31:49 -0500
Subject: ftrace: Add more checks for FTRACE_FL_DISABLED in processing ip records

From: Steven Rostedt (Red Hat) <[email protected]>

commit 546fece4eae871f033925ccf0ff2b740725ae915 upstream.

When a module is first loaded and its function ip records are added to the ftrace list of functions to modify, they are set to DISABLED, as their text is still in a read only state. When the module is fully loaded, and can be updated, the flag is cleared, and if their's any functions that should be tracing them, it is updated at that moment.

But there's several locations that do record accounting and should ignore records that are marked as disabled, or they can cause issues.

Alexei already fixed one location, but others need to be addressed.

---
 kernel/trace/ftrace.c |   22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

@@ -1856,6 +1856,10 @@ static int __ftrace_hash_update_ipmodify
 
 	/* Update rec->flags */
 	do_for_each_ftrace_rec(pg, rec) {
+
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		/* We need to update only differences of filter_hash */
 		in_old = !!ftrace_lookup_ip(old_hash, rec->ip);
 		in_new = !!ftrace_lookup_ip(new_hash, rec->ip);

@@ -1878,6 +1882,10 @@ rollback:
 
 	/* Roll back what we did above */
 	do_for_each_ftrace_rec(pg, rec) {
+
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		if (rec == end)
 			goto err_out;
 

@@ -2391,6 +2399,10 @@ void __weak ftrace_replace_code(int enab
 		return;
 
 	do_for_each_ftrace_rec(pg, rec) {
+
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		failed = __ftrace_replace_code(rec, enable);
 		if (failed) {
 			ftrace_bug(failed, rec);

@@ -3592,6 +3604,10 @@ match_records(struct ftrace_hash *hash,
 		goto out_unlock;
 
 	do_for_each_ftrace_rec(pg, rec) {
+
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		if (ftrace_match_record(rec, &func_g, mod_match, exclude_mod)) {
 			ret = enter_record(hash, rec, clear_filter);
 			if (ret < 0) {

@@ -3787,6 +3803,9 @@ register_ftrace_function_probe(char *glo
 
 	do_for_each_ftrace_rec(pg, rec) {
 
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		if (!ftrace_match_record(rec, &func_g, NULL, 0))
 			continue;
 

@@ -4679,6 +4698,9 @@ ftrace_set_func(unsigned long *array, in
 
 	do_for_each_ftrace_rec(pg, rec) {
 
+		if (rec->flags & FTRACE_FL_DISABLED)
+			continue;
+
 		if (ftrace_match_record(rec, &func_g, NULL, 0)) {
 			/* if it is in the array */
 			exists = false;

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/disable-the-__builtin_return_address-warning-globally-after-all.patch queue-4.8/ftrace-add-more-checks-for-ftrace_fl_disabled-in-processing-ip-records.patch queue-4.8/ftrace-ignore-ftrace_fl_disabled-while-walking-dyn_ftrace-records.patch